Power output system for an outboard engine

ABSTRACT

A flange portion formed on an inner periphery of a flywheel is facet-fitted to an end of a crankshaft. A spline piece is facet-fitted to an inner peripheral surface of the flywheel. The flange portion of the flywheel and a flange portion of the spline piece are commonly fastened to the end of the crankshaft by bolts. An upper end of a driving shaft is spline-fitted at a point into a driving shaft coupled portion of the spline piece which is accommodated in an internal hole in the crankshaft. Thus, in coaxially coupling the flywheel and the driving shaft to the end of the crankshaft, it is possible to make such a coupled area compact and to reduce vibration by an accurate centering thereof.

This is a divisional application of application Ser. No. 08/534,451,filed Sep. 27, 1995, now U.S. Pat. No. 5,826,464.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system for outputting power from acrankshaft, including a flywheel and a spline piece which are coaxiallycoupled to an end of a crankshaft to permit power to be output throughthe spline piece.

2. Description of the Prior Art

A power output system is conventionally known from Japanese PatentApplication Laid-open No. 138107/88, in which a common engine for a boatis commonly used in an inboard engine system including a crankshaftdisposed horizontally and in an outboard engine system including acrankshaft disposed vertically.

A power output system is also conventionally known from Japanese UtilityModel Application Laid-open No.21509/91, which includes a flywheel and atransmission shaft coupled to a lower end of a crankshaft which isdisposed vertically.

If power is output from an end of the crankshaft at which the flywheelis mounted, as in one embodiment of Japanese Patent ApplicationLaid-open No. 138107/88, or as in Japanese Utility Model ApplicationLaid-open No. 21509/91, a problem of a torsional vibration to a poweroutput shaft (corresponding to an end of the crankshaft in the priorart, and the spline piece in the present invention) by the flywheel isreduced, which is convenient as a measure to counter vibration.

Further, a power output system is conventionally known from JapaneseUtility Model Application Laid-open No.120831/83, which includes aspline piece mounted at a lower end of a crankshaft which is oppositefrom a flywheel, so that power is output.

In the power output system described in Japanese Patent ApplicationLaid-open No.138107/88, the direction of outputting power from thecrankshaft is different when the crankshaft is disposed horizontally andwhen the crankshaft is disposed vertically and for this reason, it isnecessary to adjust the rotational direction in a driven side whichreceives power from the engine. In the power output system described inJapanese Utility Model Application Laid-open No.21509/91, a transmissionis integrally incorporated immediately below the flywheel and hence, inits intact condition without modification, the mountability of the poweroutput system to another industrial machine is poor and is poor ingeneral purpose properties, and any technique for coupling anotherequipment in place of the transmission is not disclosed at all. In thesystem described in Japanese Utility Model Application Laid-open No.120831/83, the flywheel is mounted on the opposite side from the splinepiece, which is inconvenient for preventing vibration.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide ameasure to counter a torsional vibration by a flywheel having a largeinertial mass in outputting power from an end of a crankshaft by using aspline piece, and to provide an accurate centering and acompactification of the spline piece.

To achieve the above object, according to a first embodiment of thepresent invention, there is provided a system for outputting power froma crankshaft, comprising a flywheel and a spline piece which arecoaxially coupled to an end of a crankshaft to permit power to be outputthrough the spline piece. One side of the flywheel is facet-fitted to anouter periphery of an end of the crankshaft. The spline piece has aflange portion superposed on the other side of the flywheel. The splinepiece is facet-fitted to an inner peripheral surface of the flywheel andhas a spline-coupling portion which extends from the flange portiontoward the crankshaft and which is accommodated in an internal hole thatopens into the end of the crankshaft. The system further includes a boltfor commonly fastening the flange portions of the flywheel and thespline piece to the end of the crankshaft.

With the above construction, the three members: the crankshaft, theflywheel and the spline piece can be axially and radially accuratelypositioned with a reduced number of components and hence, it is possiblenot only to prevent the generation of vibration due to eccentricity, butalso to suppress the radial projection of the flange portion, connectedto the spline-coupling portion of the spline piece, to a minimum toreduce the radial size. In addition, since the spline-coupling portionof the spline piece is accommodated in the internal hole in thecrankshaft, it is also possible to reduce the axial size.

To achieve the above object, according to a second embodiment of thepresent invention, there is provided a system for outputting power froma crankshaft, comprising a flywheel and a spline piece which arecoaxially coupled to an end of a crankshaft to permit power to be outputthrough the spline piece. One side of the flywheel is facet-fitted to anouter periphery of an end of the crankshaft. The spline piece has aflange portion superposed on the other side of the flywheel. Aspline-coupling portion extends from the flange portion toward thecrankshaft and is accommodated in an internal hole that opens into theend of the crankshaft. The system further includes a bolt for commonlyfastening the flange portions of the flywheel and the spline piece tothe end of the crankshaft.

With the above construction, the three members: the crankshaft, theflywheel and the spline piece can be axially and radially accuratelypositioned with a reduced number of components and hence, it is possiblenot only to prevent the generation of vibration due to eccentricity, butalso to suppress the radial projection of the flange portion, connectedto the spline-coupling portion of the spline piece, to a minimum toreduce the radial size. In addition, since the spline-coupling portionof the spline piece is accommodated in the internal hole in thecrankshaft, it is also possible to reduce the axial size. Further, sincethe spline piece is coaxially positioned directly to the crankshaftwithout using the flywheel, the positioning accuracy of the spline pieceis further enhanced.

Further, to achieve the above object, according to a third embodiment ofthe present invention, a system for outputting power from a crankshaft,comprises a flywheel and a spline piece which are coaxially coupled toan end of a crankshaft to permit power to be output through the splinepiece. One side of the flywheel is facet-fitted to an outer periphery ofan end of the crankshaft. The spline piece has a flange portionsuperposed on the other side of the flywheel. The spline piece isfacet-fitted to an inner peripheral surface of the flywheel and has aspline-coupling portion which extends from the flange portion away fromthe crankshaft. The system further includes a bolt for commonlyfastening the flange portions of the flywheel and the spline piece tothe end of the crankshaft.

With the above construction, the three members: the crankshaft, theflywheel and the spline piece can be axially and radially accuratelypositioned with a reduced number of components and hence, it is possibleto prevent the generation of vibration due to eccentricity. It is alsopossible to suppress the radial projection of the flange portion,connected to the spline-coupling portion of the spline piece, to aminimum to reduce the radial size.

The above and other objects, features and advantages of the inventionwill become apparent from the following description of preferredembodiments taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of the entire outboard engine system incorporatinga power output system according to a first embodiment of the presentinvention;

FIG. 2 is an enlarged sectional view taken along a line 2--2 in FIG. 1;

FIG. 3 is a sectional view taken along a line 3--3 in FIG. 2;

FIG. 4 is an enlarged view of an essential portion shown in FIG. 3;

FIG. 5 is a view similar to FIG. 4, but illustrating a second embodimentof the present invention;

FIG. 6 is a side view of the entire outboard engine system incorporatinga power output system according to a third embodiment of the presentinvention;

FIG. 7 is an enlarged sectional view of an essential portion shown inFIG. 6;

FIG. 8 is an enlarged view of an essential portion shown in FIG. 7; and

FIG. 9 is a view similar to FIG. 8, but illustrating a fourth embodimentof the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of the present invention will now be described withreference to FIGS. 1 to 4.

Referring to FIGS. 1 and 2, an outboard engine system O includes a mountcase 2 for mounting and fixing a V-type 4-cylinder and 4-cycle engine Eto an upper portion of an extension case 1 which is a frame. The engineE is supported on an upper surface of the mount case 2. An under-case 3having an open upper surface is coupled to the mount case 2. An enginecover 4 is detachably mounted on an upper portion of the under-case 3.The engine cover 4 is coupled to an upper edge of the under-case 3through a seal member 5 mounted at a lower edge of the engine cover 4.The engine cover 4 is fixed by a pair of front and rear grips 6 and 7.In a condition in which a crankshaft 9 is in a vertical attitude and apair of banks 10_(R) and 10_(L) are spread rearwardly, the engine E isaccommodated within an engine room 8 defined inside the engine cover 4.

A driving shaft 12 is connected to a lower end of the crankshaft 9 ofthe engine E along with a flywheel 11. The driving shaft 12 extendsdownwardly within the extension case 1. A lower end of the driving shaft12 is connected to a propeller shaft 16 having a propeller 15 at itsrear end, through a bevel gear mechanism 14 provided within a gear case13. A lower end of a shifting member 17 is connected to a front portionof the bevel gear mechanism 14 in order to change the rotationaldirection of the propeller shaft 16.

A swivel shaft 20 is fixed between an upper mount 18 provided in themount case 2 and a lower mount 19 provided in the extension case 1. Theupper mount 18 includes a pair of arms or bolts 18a and 18b. The lowermount includes a pair of arms or bolts 19a and 19b. A swivel case 21,for rotatably supporting the swivel shaft 20, is vertically swingablysupported on a stern bracket 22 mounted at a stern S through a tiltingshaft 23.

The engine E includes a cylinder block 24 which is V-shaped as viewed ina plane, a crankcase 25 which defines a crank chamber by cooperationwith the cylinder block 24, a pair of cylinder heads 26_(R) and 26_(L)coupled to a pair of deck faces of the cylinder block 24, and headcovers 27_(R) and 27_(L) coupled to the cylinder heads 26_(R) and 26_(L)Pistons 29_(R), 29_(R), 29_(L) and 29_(L) are slidably received in twoleft cylinders 28_(L), 28_(L) and two right cylinders 28_(R), 28_(R)which are defined in the cylinder block 24. These pistons 29_(R),29_(R), 29_(L) and 29_(L) are connected to the crankshaft 9 throughconnecting rods 30_(R), 30_(R), 30_(L) and 30_(L).

The driving force of a crank pulley 31 mounted at an upper end of thecrankshaft 9 is transmitted through an endless belt 32 to a cam pulley34_(L) mounted on a cam shaft 33_(L) in the left bank 10_(L) and a campulley 34_(R) mounted on a cam shaft 33_(R) in the right bank 10_(R).

The flywheel 11 secured to a lower end of the crankshaft 9 includes agear 11₁, provided on its outer periphery, and a pinion 36 is providedon an output shaft 35₁, of a starter motor 35 and meshed with the gear11₁.

In FIG. 2, reference numeral 61 is a cartridge-type oil filter mountedin the crankcase 25. Reference numeral 62 is a magnetic switch portionof the starter motor. Reference numeral 63 is a fuel injection deviceincluding a nozzle mounted in the intake manifold inside the V-bank.Reference numeral 64 is an exhaust passage provided in the cylinderblock 24.

As can be seen from FIG. 3, the mount case 2 coupled to the lowersurface of the cylinder block 24 and the crankcase 25 by a bolt 40defines a flywheel accommodating chamber 41 which accommodates theflywheel 11. The crankshaft 9 vertically disposed is supported at itsjournal portions 9₁ on metal bearings 42 mounted between the cylinderblock 24 and the crankcase 25. The lower end of the crankshaft 9 ispassed through a seal member 43 into the flywheel accommodating chamber41. Another partition member may be provided between the mount case 2and the cylinder block 24, and the flywheel accommodating chamber 41 maybe defined between the partition member and the mount case 2.

The flywheel 11 and a spline piece 44 are commonly fastened to the lowerend of the crankshaft 9, for example, by three bolts 45 (only one isshown in FIG. 3), and the crankshaft 9 and the flywheel 11 arepositioned in a direction of rotation of a knock pin 46. An upper end ofthe driving shaft 12, extending through seal members 47, 47 into theflywheel accommodating chamber 41, is spline-fitted into the splinepiece 44.

In the embodiment, each of the driving shaft 12, the crankshaft 9 andthe spline piece 44 is made from a carbon steel, and the flywheel 11 ismade from a gray cast iron.

A power generator 49 is mounted in the flywheel accommodating chamber 41and includes a stator core 51 fixed to a lower surface of the cylinderblock 24 by bolts 50, a coil 52 wound around an outer periphery of thestator core 51, and a permanent magnet 53 fixed to an inner periphery ofthe flywheel 11 serving as a rotor.

The structure of coupling of the crankshaft 9, the flywheel 11, thespline piece 44 and the driving shaft 12 will be described below indetail with reference to FIG. 4.

An upper surface 11₂₁ of a flange portion 11₂ centrally formed on theflywheel 11 is butted against the lower end face 9₃ of the crankshaft 9into which an internal hole 9₂ axially opens. At that time, the flangeportion 11₂ of the flywheel 11 is facet-fitted (at A) to an outerperipheral surface 9₄ of the crankshaft 9, so that the crankshaft 9 andthe flywheel 11 are coaxially positioned.

The spline piece 44 includes a flange portion 44₁, and a drivingshaft-coupled portion 44₂, and an upper surface 44₁₁, of the flangeportion 44₁ is butted against a lower surface 11₂₂ of the flange portion11₂ of the flywheel 11. At that time, the spline piece 44 isfacet-fitted (at B) to an inner peripheral surface 11₂₃ of the flangeportion 11₂ of the flywheel 11, so that the flywheel 11 and spline piece44 are coaxially positioned.

In this manner, the three members: the crankshaft 9, the flywheel 11 andthe spline piece 44 are coaxially positioned by facet-fitting at twopoints A and B, and the three members are integrally commonly fastenedby threadedly inserting the bolts 45, passed from below, through theflange portion 44₁ of the spline piece 44 and the flange portion 11₂ ofthe flywheel 11 into bolt bores 9₅ in the crankshaft 9.

The upper end of the driving shaft 12 is coaxially spline-fitted (at C)into the driving shaft-coupled portion 44₂ of the spline piece 44loosely fitted in the internal hole 9₂ in the crankshaft 9.

Thus, the rotation of the crankshaft 9 of the engine E is transmittedthrough the flywheel 11 and the spline piece 44 to the driving shaft 12and then from the latter through the bevel gear mechanism 14 and thepropeller shaft 16 to the propeller 15.

As described above, the driving force of the engine E is output from theside of the flywheel 11 having a large inertial mass to the drivingshaft 12 and therefore, the torsional strength of the crankshaft 9 isconveniently increased and thus, it is possible to suppress thegeneration of vibration to a minimum. In addition, since the threemembers: the crankshaft 9, the flywheel 11 and the spline piece 44 arecoaxially positioned by the facet-fitting at the two points A and B, itis possible to prevent the generation of vibration due to eccentricityof the three members. Moreover, since the three members are commonlyfastened by the common bolts 45, the number of components is decreased.

In the prior art, after the flywheel is initially bolted to thecrankshaft, the spline piece is bolted at its outer peripheral position.In contrast, in the system according to the present invention, theprojection of the flange portion 44₁ of the spline piece 44 issuppressed to a minimum by the common fastening of the three members bythe common bolts 45, thereby achieving a reduction in size of the poweroutput area, leading to enhanced general-purpose properties.

Further, since the spline piece 44 is facet-fitted at B by utilizing theinner peripheral surface 11₂₃ required in processing the flywheel, it isunnecessary to define a special hole for facet-fitting of the splinepiece 44 to the flywheel 11, leading to a decreased number of processingsteps. Since the driving shaft-coupled portion 44₂ of the spline piece44 is accommodated in the internal hole 9₂ in the crankshaft 9, it ispossible not only to reduce the axial size of the power output area, butalso to minimize the radial projection of the flange portion 44₁connected to the driving shaft-coupled portion 44₂ to reduce the radialsize of the power output area.

A second embodiment of the present invention will now be described withreference to FIG. 5.

Although the spline piece 44 has been coaxially positioned to theflywheel 11 by the facet-fitting at B in the previously-described firstembodiment, the spline piece 44 is coaxially positioned directly to thecrankshaft 9 in the second embodiment. More specifically, the outerperiphery of the driving shaft-coupled portion 44₂ of the spline piece44 is not in direct contact with the inner peripheral surface 11₂₃ ofthe flywheel 11, and a radial gap α is provided therebetween. The outerperiphery of the driving shaft-coupled portion 44₂ of the spline piece44 is faucet-fitted at D into the internal hole 9₂ in the crankshaft 9and coaxially positioned to the crankshaft 9.

In the second embodiment, an operational effect similar to that in thefirst embodiment can be provided, and in addition, the spline piece 44can be coaxially positioned directly to the crankshaft 9 without usingthe flywheel 11, and axes of the crankshaft 9 and the spline piece 44can be further accurately aligned with each other.

The spline piece 44 is axially positioned with its flange portion 44₁abutting against the flange portion 11₂ of the flywheel 11 andtherefore, the faucet-fitting D of the driving shaft-coupled portion 44₂of the spline piece 44 and the crankshaft 9 may be such that there is anaxial gap β therebetween. Further, the driving shaft-coupled portion 44₂of the spline piece 44 may be only simply fitted into the internal hole9₂ in the crankshaft 9. In short, the driving shaft-coupled portion 44₂of the flywheel 44 needs only to be radially positioned relative to theinternal hole 9₂ in the crankshaft 9 and thus, the processing cost forthe internal hole 9₂ in the crankshaft 9 can be reduced.

A third embodiment of the present invention will now be described withreference to FIGS. 6 to 8, wherein members or components correspondingto those in the first and second embodiments are designated by likereference numerals.

As shown in FIG. 6, an outboard engine system O includes a mount case 2coupled to an upper portion of an extension case 1. A serial 4-cylinderand 4-cycle engine E is supported on an upper surface of the mount case2. An under-case 3 having an open upper surface is coupled to the mountcase 2. An engine cover 4 is detachably mounted to an upper portion ofthe under-case 3. A lower edge of the engine cover 4 is coupled to anupper edge of the under-case 3. An under-cover 5 is coupled between alower edge of the under-case 3 and an upper edge of the extensioncase 1. Thus, in a condition in which a crankshaft 9 is in a verticalattitude, the engine E is accommodated within an engine room which isdefined inside the engine cover 4.

A driving shaft 12 is connected to a lower end of the crankshaft 9 ofthe engine E along with a flywheel 11. The driving shaft 12 extendsdownwardly within the extension case 1. The driving shaft 12 isconnected at its lower end through a bevel gear mechanism 14 mountedwithin a gear case 13 to a propeller shaft 16 having a propeller 15 atits rear end. A lower end of a shifting member 17 is connected to afront portion of the bevel gear mechanism 14 in order to change thedirection of rotation of the propeller shaft 16.

A swivel shaft 20 is fixed between an upper mount 18 provided in themount case 2 and a lower mount 19 provided in the extension case 1. Aswivel case 21, for rotatably supporting the swivel shaft 20, isvertically swingably supported through a tilting shaft 23 on a sternbracket 22 mounted at a stern S.

The engine E includes a cylinder block 24, a crankcase 25 which definesa crank chamber by cooperation with the cylinder block 24, a cylinderhead 26 coupled to a deck face of the cylinder block, and a head cover27 coupled to the cylinder head 26. Pistons are slidably received infour cylinders 28 defined in the cylinder block 24, respectively, andare connected to the crankshaft 9 through connecting rods 30.

As can be seen from FIG. 7, the mount case 2, coupled to lower surfacesof the cylinder block 24 and the crankcase 25, defines a flywheelaccommodating chamber 41 which accommodates the flywheel 11 therein.Journal portions 9₁ of the crankshaft 9, disposed vertically, aresupported on metal bearings 42 which are mounted between the cylinderblock 24 and the crankcase 25, and a lower end of the crankshaft 9 ispassed through a seal member 43 into the flywheel accommodating chamber41. The flywheel 11, secured to the lower end of the crankshaft 9,includes a gear 11 around an outer periphery thereof. A pinion 36,provided on an output shaft 35₁ of starter motor 35, is meshed with thegear 11₁.

The flywheel 11 and the spline piece 44 are commonly fastened to a lowerend of the crankshaft 9, for example, by three bolts 45 (only two areshown in FIG. 7). An upper end of the driving shaft 12, extendingthrough a seal member 47 into the flywheel accommodating chamber 41, isspline-fitted into the spline piece 44.

The structure of coupling of the crankshaft 9, the flywheel 11, thespline piece 44 and the driving shaft 12 will be described below indetail with reference to FIG. 8.

An upper surface (or first side) 11₂₁ of a flange portion 11₂ centrallyformed on the flywheel 11 is butted against a lower end face 9₃ of thecrankshaft 9. At that time, the flange portion 11₂ of the flywheel 11 isfacet-fitted (at A) to an outer peripheral surface 9₄ of the crankshaft9, so that the crankshaft 9 and the flywheel 11 are coaxiallypositioned.

The spline piece 44 includes a flange portion 44 and a drivingshaft-coupled portion 44₂, and an upper surface 44₁₁, of the flangeportion 44₁ is butted against a lower surface (or second side) 11₂₂ ofthe flange portion 11₂ of the flywheel 11. At that time, the splinepiece 44 is facet-fitted (at B) to an inner peripheral surface 11₂₃ ofthe flange portion 11₂ of the flywheel 11, so that the flywheel 11 andspline piece 44 are coaxially positioned.

In this manner, the three members: the crankshaft 9, the flywheel 11 andthe spline piece 44 are coaxially positioned by facet-fitting at twopoints A and B, and the three members are integrally commonly fastenedby threadedly inserting the bolts 45, passed from below, through theflange portion 44₁ of the spline piece 44 and the flange portion 11₂ ofthe flywheel 11 into bolt bores 9₅ in the crankshaft 9.

The driving shaft-coupled portion 44₂ of the spline piece 44 extendingfrom the flange portion 44₁ in a direction away from the crankshaft 9 iscylindrically formed. An outer periphery of the driving shaft 12 at itsupper end is coaxially spline-fitted (at C) to an inner periphery of thedriving shaft-coupled portion (or spline coupling portion) 44₂.

In this embodiment, the flywheel 11 is made of a gray cast iron, andeach of the crankshaft 9, the driving shaft 12 and the spline piece 44is made of a carbon steel.

Thus, the rotation of the crankshaft 9 of the engine E is transmittedthrough the flywheel 11 and the spline piece 44 to the driving shaft 12and then from the latter through the bevel gear mechanism 14 and thepropeller shaft 16 to the propeller 15.

As described above, the driving force of the engine E is output from theside of the flywheel 11 having a large inertial mass to the drivingshaft 12 and therefore, the torsional strength of the crankshaft 9 isconveniently increased and thus, it is possible to suppress thegeneration of vibration to a minimum. In addition, since the threemembers: the crankshaft 9, the flywheel 11 and the spline piece 44 arecoaxially positioned by the facet-fitting at the two points A and B, itis possible to prevent the generation of vibration due to eccentricityof the three members. Moreover, since the three members are commonlyfastened by the common bolts 45, the number of components is decreased.

In the prior art, after the flywheel is initially bolted to thecrankshaft, the spline piece is bolted at its outer peripheral position.In contrast, in the system according to the present invention, theprojection of the flange portion 44₁ of the spline piece 44 issuppressed to a minimum by the common fastening of the three members bythe common bolts 45, thereby achieving a reduction in size of the poweroutput area, leading to enhanced general-purpose properties.

Further, since the spline piece 44 is facet-fitted at B by utilizing theinner peripheral surface 11₂₃ required in processing the flywheel, it isunnecessary to define a special hole for facet-fitting of the splinepiece 44 to the flywheel 11, leading to a decreased number of processingsteps. Since the upper end of the driving shaft-coupled portion 44₂ isfitted to the inner peripheral surface 11₂₃ of the flywheel 11, it ispossible to ensure the spline length of the driving shaft-coupledportion 44₂ without an increase in vertical size.

A fourth embodiment of the present invention will now be described withreference to FIG. 9.

Although the driving shaft-coupled portion 44₂ of the spline piece 44has been cylindrically formed, and the driving shaft 12 is spline-fittedto the inner periphery of the driving shaft-coupled portion 44₂ in thethird embodiment, the driving shaft-coupled portion 44₂ of the splinepiece 44 is formed into a rod-like shape, and the driving shaft 12 isspline-fitted at C to the outer periphery of the driving shaft-coupledportion 44₂ in the fourth embodiment.

In the fourth embodiment, an operational effect similar to that in thethird embodiment can be provided. However, the spline length of thedriving shaft-coupled portion 44₂ is slightly shorter than that in thethird embodiment.

Although the embodiments of the present invention have been described indetail, it will be understood that the present invention is not limitedto the above-described embodiments, and various modifications in designmay be made without departing from the spirit and scope of the inventiondefined in claims.

For example, the output of power from the crankshaft of the engine inthe outboard engine system has been illustrated in the embodiments, butthe present invention is also applicable to the output of power from acrankshaft of any other type of engine E.

More specifically, the present invention is applicable to an engineincluding a jet pump having a nozzle in a rear of a stern mounted on asmall-sized boat, and a crankshaft is spline-coupled to an intermediateshaft which is connected directly to an impeller shaft or through adamper. In addition, the present invention is applicable to an enginewhich is connected to a power generator having a coil mounted on one ofa rotor and a stator to constitute a generator motor, and a shaft of therotor and the crankshaft are spline-coupled to each other. Further, thepresent invention is also applicable to an engine working machine and apump in other fields, wherein wide general-purpose properties areexhibited by the consideration of the vibration and by a reduction insize of the spline piece.

Additionally, the present invention is applicable to an engine includingcylinders disposed in a V-shaped arrangement within a single cylinderblock, and also to any of a 2-cycle engine and a 4-cycle engine.

What is claimed:
 1. An outboard engine device having an internalcombustion engine and a power output system, said engine comprising acrankshaft disposed vertically and a plurality of cylinders with pistonsslidably received therein, respectively, said power output systemcomprising:a flywheel; and a spline piece; wherein said flywheel andsaid spline piece are coaxially coupled to a lower end of saidcrankshaft to permit power to be output through said spline piece;wherein said flywheel has opposite upper and lower sides, the upper sideof the flywheel being facet-fitted to an outer periphery of said lowerend of the crankshaft, and said spline piece has a flange portionsuperposed on the lower side of the flywheel, said spline piece beingfacet-fitted to an inner peripheral surface of the flywheel and saidspline piece having a spline-coupling portion which extends from saidflange portion away from the crankshaft; and wherein at least one boltis used for commonly fastening said flange portion of the flywheel andsaid spline piece to said lower end of the crankshaft.
 2. A system foroutputting power from a crankshaft according to claim 1, wherein saidspline-coupling portion having an inner periphery formed with aninternal spline.
 3. A system for outputting power from a crankshaftaccording to claim 1, wherein said spline-coupling portion is formed atan outer periphery thereof with a spline.
 4. A system according to claim1, wherein an inner periphery of said spline-coupling portion isspline-fitted to a driving shaft.
 5. A system according to claim 1,wherein an outer periphery of said spline-coupling portion isspline-fitted to a driving shaft.
 6. A system according to claim 1,wherein said spline-coupling portion is cylindrically formed.
 7. Asystem according to claim 1, wherein the spline-coupling portion isformed into a rod.
 8. An outboard engine device having a frame means, aninternal combustion engine carried on said frame means, a power outputsystem, a drive shaft for receiving power from said power output system,a first shaft for tilting motion of said outboard engine device and asecond shaft for steering operation of the outboard engine device via abracket means, said engine comprising a crankshaft disposed verticallyand a plurality of cylinders with pistons slidably received therein,respectively, wherein a pair of upper mount elements are interposedbetween said bracket means and said frame means, said power outputsystem comprising:a flywheel; and a spline piece; wherein said flywheeland said spline piece are coaxially coupled to a lower end of saidcrankshaft to permit power to be output through said spline piece;wherein said flywheel has opposite upper and lower sides, the upper sideof the flywheel being facet-fitted to an outer periphery of said lowerend of the crankshaft, and said spline piece has a flange portionsuperposed on the lower side of the flywheel, said spline piece beingfacet-fitted to an inner peripheral surface of the flywheel and saidspline piece having a spline-coupling portion which extends from saidflange portion away from the crankshaft; wherein at least one bolt isused for commonly fastening said flange portion of the flywheel and saidspline piece to said lower end of the crankshaft; and wherein saidspline piece and said drive shaft are connected with each other at alocation between said pair of upper mount elements.
 9. A system foroutputting power from a crankshaft according to claim 8, wherein saidspline-coupling portion having an inner periphery formed with aninternal spline.
 10. A system for outputting power from a crankshaftaccording to claim 8, wherein said spline-coupling portion is formed atan outer periphery thereof with a spline.
 11. A system according toclaim 8, wherein an inner periphery of said spine-coupling portion isspline-fitted to a driving shaft.
 12. A system according to claim 8,wherein an outer periphery of said spline-coupling portion isspline-fitted to a driving shaft.
 13. A system according to claim 8,wherein said spline-coupling portion is cylindrically formed.
 14. Asystem according to claim 8, wherein the spline-coupling portion isformed into a rod.